The result is not just a medical degree, but becoming an extreme ski champion, founding a fast-growing medical recruitment business, MedRecruit, being crowned Young Entrepreneur of the Year by Ernst & Young in 2012, and most recently, writing a book aimed at boosting the success of small- and medium-sized businesses.
Out today, Unfair Fight: give your small business the winning advantage is the distillation of Hazledine's experience creating his own company and the lessons he's learned from other business leaders.
He says most New Zealand businesses have fewer than 20 staff but are going up against much larger competitors.
"They're competing with the big corporates; they're competing with the big guy as if it's a level playing field, so they're going head-to-head using similar tactics, similar strategies, trying to emulate the big guy - and if you go head-to-head with a giant you're going to get crushed."
Taking a different approach, like David in his battle with Goliath, is the only way to stack the odds in your favour, Hazledine says.
With so many business books aimed at big firms, Unfair Fight sets out the techniques smaller companies can use to land the knockout punch.
He says the reality for most small business owners is that they are working hard at a poorly paid job. But one of the saddest things Hazledine says he sees is businesses pouring that enthusiasm into the wrong place.
"These are my lessons. These are the things that I've learnt and applied to build the fastest growing service firm in the country and they're also lessons from really, really smart people."
Unfair Fight also devotes a lot of attention to getting your head straight.
"I believe that success lies at the intersection of mindset and action - you need to have both," says Hazledine.
"If you don't get your mindset, if you don't get your psychology in the right place, then none of that stuff works."
After his head injury Hazledine set about raising his standards - initially just to get back on his feet - but quickly realised that by living a different way he could get better results from his life.
"The difference between setting goals and raising your standards is goals come and go.
"I think the purpose of the goal is not to achieve the goal, it's to become the person you need to be to achieve the goal and that's what raising your standards is.
"It's about becoming the person you need to be."
He says the wins and business achievements are the icing on the cake, but the "guts of the cake" is the person you become to achieve those goals.
Hazledine says the accident made him reflect on whether he was living his life with purpose, passion and presence, attributes he recognised in people he respected.
He says they were people doing what they loved, making a real difference and doing it with excellence.
"These people are not caught up in the minutiae of life. They're not spending all their time on Facebook."
Part of the motivation for writing the book was to answer the question of living his life with purpose.
"I feel that I have an obligation that with financial success comes some responsibility to do something positive with that and make a difference with that."
Unfair Fight is part of that contribution by providing a resource for building successful enterprises to the business community.
A spin-off effect will be felt in Africa.
Hazledine has pledged the proceeds from the book towards a special project run by American gang member-turned-Christian Sam Childers, aimed at rescuing children caught up in the conflict in South Sudan. "It's giving those little guys a chance."
